Rotary pump



D. APPEL ROTARY PUMP Filed Nov 14, 1931. 4 Sheets-Sheet 1 .FHNIE'L HPPELD. APPEL ROTARY PUMP May 23, 1933.

Filed Nov. 14, 1931 i 4 Sheets-Sheet 2 4 Sheets-Sheet 3 D. APPEL ROTARYPUMP Filed Nov. 14,

May 23, 1933.

May 23, 1933-. APPEL 1,510,376 ROTARY P UMP Filed Nov. 14. 1951 4Sheets-Sheet 4 risn .vnma'z. IIFPEL INVENTOR I ATTCRNEY 1,853,394 datedApril 12, 1932,.in which a stone, which are reciprocated by a crankPatented May 2 3, 1933 UNITED STATES PATENT OFFICE DANIEL APPEL, OF EASTCLEVELAND, OHIO, ASSIGNOR TO LE ROY A. WEST'MAN AND GLENN 1B. CARMAN,BOTH OF CLEVELAND, OHIO nanny rum? Application filed November '14, 1931.

This invention relates to rotary pumps of the type described in myLetters Patent No.

rotatable cylinder or rotor is mounted in a casing and carries andsupports a set of-pisshaft or eccentrics in offset relation with respectto the axis of the rotor andtransfer the rotary movements thereof to therotor.

I have found that these pumps, in which each stroke of the pistonscorresponds to half a revolution of the rotor and to a completerevolution of the crank shaft or eccentrics, work satisfactorily onlywhen certain definite relative dimensions of the rotor diameter and thepiston strokes are maintained, the latter being in turn governed by thecrank shafts or eccentrics;

The general object of the presentinvention is to define such relationsand the limits withinwhich practical results may be obtained from arotary pump of the type described. I have found that the relationshipbetween the rotor diameter of the pump and the piston stroke must fallapproximately above ratios 3 ,to land that pumps of highest efliciencyshould, have approximately between 4.3 to 1' and 6 to 1. The limitationsin the ratios described above are necessary for the followin reasons.

Pumps of the ind described, when rotated at low speeds, do not work withuniform pressure as the movement of thepistons dur- V ing eachrevolution of the cylinder is variable. In order to overcome suchdisadvantages and to produce a uniform pressure at the outlet side ofrotary pumps it is necessary to run the same with high speed, at

least over two hundred revolutions per minute. Such speed of the rotorof course increases the amount of liquid discharged and necessitates adecrease of the cross section of the piston, in order to avoid twistingof the crank shaft. Any decrease in the cross section of the piston ofcourse decreases the necessary bearing between piston and crank shaftand makes pumps with ratios below 3 to 1 impractical, and useless,particularly smaller pumps with a rotor diameter below 3 inches. I

Serial No. 575,088,

Pumps with higher ratios, say beginning with approximately above 7 to 1become more and more inelficient because of marked binding tendencybetween the pistons andthe rotor. ,Thus, with higher ratios betweenrotor diameter and piston stroke the distance between the axis of therotor and the axis of the crank shaft and therewith the leverage of thecrank shaft tending to rotate the rotor shortens, to such an extent thatsubstantially higher driving power is required.

This increase in driving power increases the friction between thepistons and their chambers so that the force required to rotate for usein the oiling systems of aeroplanes,

refrigerating plants, etc.

The invention will better be understood 1 from thefollowing descriptionof a-rotary pump and the diagrams shown in the aplongitudinally of apump of the described type, excepting the shaft which is shown inelevation. Fig. 2 i s an end elevation ofa pump with the end plate orcover removed, and Fig. 3 a vertical section of the pump on line 3-3 ofFig. 1. Fig. 4 is a similar sectional view on line 4-4 of Fi 1. Fig. 5is a sectional view of a modi ed form of pump, embodying the invention,and Figs. 6 and 7 p are side and end elevations of the rotatablecylinder or rotor of the pump shown in Fig. 5. Fig.8 is a side view ofthe drive shaft and Figs. 9 and 10 are elevations of the separatepistons actuated by the drive shaft. Fig. 11 is asectional view of apump of the type shown in Figs. 5 through 10 provided with a splitrotor.Fig. 12 is a sectional View of the rotor and Fig. 13 a side view of thesplit rotor. Fig. 14 is a side view of the drive shaft, and Figs. 15 and16 elevations of the separate pistons actuated by the drive shaft. Fig.17 is a diagrammatical view showing the change of leverage during one Asdelineated in Figs. 1 through 4, the

pump comprises a cylindrical 'body 2 containing a circular chamber 3.One end of this chamber is closed by an integral wall of the casing, andthe opposite end by a removable head or plate 4, or both ends of thecasing may be rovided with removable heads if desired. eparate inlet andoutlet ports or passages 5 and 6, respectively, are provided within body2 at opposite sides of circular chamber 3, each port extendingcircumferentially of the chamber for a substantial distance, sayapproximately ninety degrees, thereby leaving a closed area ofapproximately the same are at the top and bottom of the chamber betweenthe two ports. A shaft 7 extends through body 2, one end havingrotatable bearing within plate 4 where a hollow gland member 8 andpacking materials are provided to prevent leakage. Gland member 8 isfilled with a lubricant, and a certain degree of suction is producedinthis pump which feeds the lubricant to the working parts throughsuitable ducts or passages 9 inthe shaft. The opposite end of shaft 7extends through a second gland member 10 fastened by screws or bolts 11to body 2, and a drive pulley or gear (not shown) may be fastened to theexposed end of the shaft; or any drive coupling may be used. Twocircular eccentrics 12-12 form integral parts of shaft 7 where they mayrevolve in separate orbits side by side within circular chamber 3L Theseeccentrics are one hundred and eighty degrees apart, the centers beingequally distant from the axis of the shaft, which is offset oreccentricallyrelated to the axis or center .of circular chamber 3. Thedegree of offset or eccentricity of shaft 7 to the center of chamber 3is exactly one-half ofthe radius of orbital travel of each eccentric12-12'. As a result the circular orbit of each eccentric 12-12, asdefined by the center of the eccentric, touches the axis or center ofcircular chamber 3. This relationship of parts is essential, otherwiserotatable movement of the rotor member 14, as hereinafter described,cannot occur.

Rotor member 14 is cylindrical and rotates Within chamber 3 with a closefit at its circumference and its opposite ends. The center of itsrotative movement is therefore the axis or center of chamber 3. Rotationis imparted to rotor member 14 by both eccentrics 12 12 when power isapplied to revolve shaft- 7. A pair of power translating elements,herein also referred to as pistons, 1515 respectively, are rotatablyconnected or coupled to the eccentrics 1212. Thus, each' piston has acircular opening therein within which its eccentric fits, the oppositeends of the piston being curved or rounded in the same degree ascircular chamber 3, although not necessarily. The piston may be either aflat bar or block, as shown in Figs. 1 through 4, or it may be ofcylindrical form. This piston embodies two parallel straight sides oredges equally distant from the center of the bushed opening therein.Rotor member 14 is formed with two straightsided channels 16-16extending diametrically across the flat end faces thereof, and lie atright angles, or in other words, are quartered in respect to the circle.Piston 15 within channel 16 is shown at one end of its stroke. Also, thetwo eccentrics 12-12 are centered in the same vertical plane as thecenter of rotatable member 14, and in that relationship of parts takenote that the center of circular eccen tric 12 is co-incident with thecenter or axis of rotor member 14. This is a dead center position forthat piston and rotor member 14 wherefor in the absence of a secondeccentric differently positioned, a binding or looking action would takeplace, thereby either preventing or interfering with the free rotationof rotor member 14. In connection with the foregoing also observe thateach eccentric is circular and can only revolve within the circularopening in the piston with which it is coupled, and that no slot is usedin the piston to permit other play or movement between the eccentric andthe piston.

In operation, when shaft .7 is rotated the two eccentrics 1212"co-actwith the two pistons 15 15 to revolverotor member 14. Two revolutions ofthe shaft are required to produce one revolution of the rotor member.The pistons are carried around with the rotor member and are moved backand forth within their respective channels or working chambers by theeccentrics, each single revolution of the rotor member producing aforward stroke and a return stroke of the pistons.

' circular wall of a casing. The revoluble shaft and its eccentricsproduce such oscillatory movement of the pistons. In addition thepistons are carried around by the rotor in an orbit eccentric to thecircular wall of the cas- The relative proportions of the working partsof the rotary pumps described herein must come within certain limits, inorder to produce a practical and eflicient structure. Thus, the ratio ofthe diameter of the rotor 03 to the length of the piston stroke 1 shouldbe equal to or above3to1as best understood from diagrams of Figs. 17through 19. The dlagram of Fig. 19 shows the change of leverage forpumps of different ratios, that is, pumps having a ratio of 3 to 1, 6 to1, and 12 to 1.

It will readily be seen that a decrease of the piston stroke causes adecrease in the size of the eccentrics and that a pump with a ratio.

lower or substantially lower than 3 to 1 is impractical because of thedecreased bearing for the eccentric, which bearing becomes too 'small towithstand the heavy wear incident to continuous use of the pump andbecause of the heavy shocking and hammering action of the pistons, whichis increased with increasing piston stroke and increased speed of thepistons.

In pumps with ratios say about 10 to 1, the leverage applied to therotor for rotating same has decreased to such an extent that thenecessarily increased driving power begins to tilt the pistons and rotorwithin the limits of their clearance (the clearance between rotor androtor housingand pistons and piston chamber) thereby effectingsubstantial friction and finally binding between the pistons and theirchambers so that the pump becomes inoperative. The binding action of thepistons depends of course upon'the pressure present at the outlet sideof the pump.

In the modified form of pump shown in Figs. '5 to 10, the samecharacters used in Figs. 1 to 4, in-- asmuch as the working parts arerelated and operate in the same ,way, anddiffer only in shape and form.Thus, the casing is of greater length, and the rotor member is anelongated cylindrical body instead of a flat disk. This cylinder is notchanneled at its ends but is formed instead with a pair of circularopenings or chambers 18, 18 spaced apart and extending at right angles.diametrically through the body. Accordingly,-

.structure is shown in Fi like parts are designated by' ly,thepreviously mentioned binding action of the pump is not avoided.

In pumps of the t pe described it is necessar that the central opening22 be contmu ous y covered by the pistons and never openly exposed sothat a flowing ofllquld from one cylinder chamber into the other cannottake place. This necessity renders it 1mpossible to build a structure asshown in Fi s. 5 through 10 with a ratio below 5 to 1, as t e assemblyof the rotor with its pistons can only .be accomplished by axiallyshifting the drive shaft 7 through central opening 22 of the rotor andthe circular openings in pis tons 19-19. To permit such assemblyproceedings central'opening 22 must be of such cross section that thedrive shaft 7 with eccentrics 12-12 may readily be rotated therein.Furthermore, the lateral distance between the piston chambers must beapproximately equal to the piston diameter to permit rotation of thedrive shaft into proper alignment of its eccentrics with respect to thecircular openings of pistons 1-9-19' after one of the eccentrics hasbeen shifted through the circular opening of one of the pistons.Consequently, pumps with a ratio below 5 to l-mu st be provided with anopening of such size that the reciprocatory pistons do not.

continuously cover same and, are. therefore impractical.

The structure of Figs. 5 through 10 has a ratio of approximately 6 to 1.In'order to build pumps of this type with a ratio below 5 to 1 the rotormust be split to enable assembly with a smaller central opening. ,Suchgs. 11 through 16 in which like parts are designated by the samecharacters used in Figs. 1"to' 4. As shown, the rotor member of thisstructure, an elongated cylinder embodies two inter-connected parts 23and 24;,each ofwliich is formed with a circular opening or chamber 25,25 respectively. These parts, 23 and 24, are interlocked against lateralcentral extension 28 of face 26' of part 24.

simultaneously align parts 23, 24 by means of dowel portions 30. Theaxial opening 31 of the assembled rotor is equal in cross section to the.size of the eccentrics 12-12 of the drive shaft and permits building ofsuch pump with ratios of 3 to 1 without exposing the central-openingduring the reciprocatory movements of the pistons.

Q viously, the dimensions of the machine may also be changed and morethan two pistons employed in av single rotor member b merely extendingthe length of the cylindrimovement. Thus, the face 26 of: part 23 isrecessed and surrounds -w1th its circumferential flange portion 27, a

cal casing and rotor member, and duplicating the parts. Roller or ballbearings may be used, and other modifications.

What I claim, is:

1. A rotary pump having a cylindrical casing, a rotor within said casinghaving a central bore extending longitudinally through said rotor, aseries of chambers within said rotor diametrically thereof and closelyand angularly related to each other, a piston for each of said chambersand integral rotatable driving means eccentrically mounted withrespectto the axis of said rotor including enlarged eccentric portionsangularly related to each other and coupled with said pistons centrallythereof, the eccentricity of said driving means with respect to saidaxis of said rotor being such that the ratio of the rotor diameter tothe piston stroke of said pistons is above 3 to -1 and said rotor beingmade in separate interconnected sections, axially aligned with eachother, and each of said sections including a piston chamber to permitassembly of the rotor, pistons and driving means.

2. A rotary pump having a cylindrical casing, a rotor within said casinghaving a central bore extending longitudinally through said rotor, aseries of chambers within said rotor diametrically thereof and angularlyrelated to each other, a piston for each of said chambers and integralrotatable driving means eccentrically mounted with respect to the axisof said rotor includingenlarged eccentric portions fitting said centralbore and angularly related to each other and coupled with said pistonscentrally thereof, said adjoining chambers in said rotor being spaced :1distance equal to their cross section to permit assembly of said rotor,pistons and drive shaft with the small central bore through said rotor.

In testimony whereof I affix my signature.

DANIEL APPEL.

